Love your best friend
by PinkPunk010
Summary: AU: When did she stop depending on him, and start loving him? Harry Sullivan was the one person she could depend upon. And Sarah-Jane Smith was always the one woman he would do anything for. Shamelessly AU.
1. Chapter 1

**A/N I just watched Terror of the Zygons. Now, being from a military family myself, I know that the black and gold getup that Harry was in were Navy ones. I thought it ever so unfair that he has to run around in his smartest parade uniform while UNIT are in their combat gear! Poor Harry. I also had a bit of an issue with how they didn't even say goodbye to Harry when they left him in Scotland S-J and the Doctor knew that they would never end up in London! **

**Anyway, moan over. I had a nap today when I got back from my lectures, one of the biggest mistakes ever because it is now really late and I am really not tired!**

**This Is completely and proudly AU. **

**Disclaimer: I don't own Dr Who. That courtesy goes to the BBC. **

…..

He isn't sure when they stopped being best friends. Not while travelling with the Doctor at least. Those few days, no sleep, in the same clothes, being buffeted from planets to spaceships via somewhere else just to get back to the TARDIS were far too rushed for anything other than an everlasting friendship to form. It's like being in a warzone, your comrades become closer to you than anything in civilian life. It's a shared experience. Only they know what you feel about being in x situation or y high stress emotional state. You depend upon them in the instance to have your back and to get you out if necessary.

And that's how it felt with Sarah. She was his comrade, his brother in arms. She got his out of mischief, and she got him into scrapes too. You can't travel in the TARDIS and not know that, no matter what, that person will be there for you if you call.

So she called. It was several months after he had stood, splendid in his Navy Uniform, with the Doctor saying that he could hop back to London and offering a lift. Harry had thought she wouldn't go for the briefest second but he knew that Sarah would always go looking for trouble. He didn't envy her, he just hoped, when she did decide that the TARDIS life was no longer for her, that the Doctor would drop her back in a time where he, and Benton, and Lethbridge-Stewart could watch out for her.

And he dropped her off in Aberdeen, with no money and a box full of possessions. With her last pence in the bottom of a coat, she had called him and asked if he could see about getting someone to pick her up.

Harry had gone to the Brigadier, told him what had happened and requested immediate leave and use of a vehicle. The Brigadier had agreed instantly. Good chap.

Sarah had made friends with a local landlady while she was in Aberdeen so had been well looked after by the time Harry had pulled up, very late at night. Sarah had still been awake, waiting for him (time travel did give one the most dreadful jet lag) and he could see her shoulders sag in relief when he arrived. They had both slept very well, Harry settling the bill (despite Sarah's insistence of course) and started on the long old journey back to London. Sarah told him of adventures she'd had, of creatures she had faced that he once wouldn't have been able to imagine, of the people she had met. Around Sheffield, she had stopped talking, just staring quietly out the window at the changing landscape. Harry hadn't pushed her, Sarah never did respond well to that.

"Why didn't he check?" She said quietly, some agonisingly quiet miles later. "Why did he just leave me there?"

"I don't know Sarah," Harry had sighed, reaching across to put one of his hands on hers, folded in her lap as they were. He pulled back to drive. "Why did you want to come home?"

"I didn't," she said quietly, turning her face so he wouldn't see the tears in her eyes. She didn't say anything until they arrived at UNIT. And then she went back to a more withdrawn and quiet version of her own self. She joked with the Brigadier half heartedly, and chuckled at something Benton said about Harry's driving.

Harry was given leave for the rest of the week. Sarah had worried the Brigadier exceedingly, and Harry knew that he would be having a few words with the Doctor right about now if he could.

She never gave up of course, good old Sarah. Kept waiting for him to arrive, to insist that they go running away to amazing worlds in that blue box of his. She depended on Harry to help her adjust to having to work, to pay bills, to having to cook and shop and socialise again.

Maybe that was when it changed. When she found 'Old girl' an endearment instead of threatening to spit in his face or something.

…..

"Hallo Miss Smith," Harry smiled charmingly, as he usually did upon opening the door to see Sarah's formidable aunt. Since her return from the States, Lavinia had once again taken up residence in the Smith household, and Sarah, was in fact the guest. Harry had decided to not try to make friends with the (quite frankly terrifying) woman. "Is Sarah in?"

He felt a little bit like a schoolboy again, running into the village to see his friends.

"Coming Harry!" Sarah had cried out, struggling to put a coat on and hang onto her bag at the same time. She threw him her hat for a second, succeeding in slipping both arms into the cream contraption she was attempting to wear. He chuckled at her, shaking his head affectionately.

"You alright there old girl?" he teased with a light laugh, leaning against the doorframe. She shot him a winning smile and laughed, stretching up to kiss her aunt's bony cheek before stooping to pick up a small suitcase.

"I am quite fine thank you Harry," She had practically sang, handing him her suitcase in exchange for the hat that she crammed onto her head. "Goodbye Aunt Lavina, I shall see you on Sunday."

Lavinia harrumphed, watching her niece with narrowed eyes. She didn't believe for a second that there was 'nothing going on' in that unusual relationship. Sarah was all for independence, and solidarity, and she didn't bat an eyelid to the handsome military doctor from calling her 'old girl'. Yes, something was definitely up.

Harry was escorting Sarah to a conference in London, a medical conference (which was why she had asked him to come too, he would be able to tell her what it all meant) that she had been asked to write an article on. She was doing well as a freelance journalist. Very well.

"I thought we might stop off for a bite to eat on the way," Harry smiled at her, "my treat of course."

"Oh, of course!" Sarah mimicked good naturedly. "But I feel I must protest, I do believe that it was upon my suggestion that we partake in this adventure in the first place."

"Oh, hardy har," Harry said, faux crossly. "I don't sound a thing like that!"

"I don't sound a thing like that!" Sarah mimicked with a laugh. "Of course you don't Harry dear, you just keep telling yourself that!"

…

_Bring Bring. _Harry hated whoever it was who needed him at this precise moment. It was hardly even four o'clock for heavens sake. He hoped they would just give up. But no. _Bring Bring. Bring Bring._

Groaning, Harry sat up, and lifted the receiver to his ear. "Hello?" he said groggily.

"_Harry?"_ Sarah said down the phone, she sounded like she had been crying. Harry instantly woke up a bit more, and began trying to locate his shoes and socks while keeping the phone cradled between his ear and shoulder.

"Sarah?" He asked. "What's up old thing?"

"_Aunt – Aunt Lavina has – has , oh Harry_," She broke down into hiccupping tears again.

"Where are you?" He said quickly, "I'll come and get you."

"_London Memorial Hospital," _She had sobbed. The fact she brokered no argument at all worried Harry greatly.

"Sarah," he said gently, "What's happened to your Aunt?"

"_She's had a heart attack,"_ Sarah hiccupped, "_Please Harry…"_

"I'm on my way old girl," He said in as soothing a manner as he could. "You hang on in there old girl. Ok? Wait outside the doors for me."

"_Ok Harry," _Sarah had said quietly_ "Thank you."_

"Don't need to thank me Sarah," He said seriously. "I'll be there as soon as I can."

Then he had hung up, shoved a few clothes into a carrybag, had slipped a dressing gown on over his pajamas and left immediately. When he'd parked in the hospital carpark, he cast a glance toward the entrance. And when he realised that the tiny, huddled figure in a too big jumper and trousers was Sarah, his heart broke a little. Sarah and her Aunt may not have gotten on, but Lavina was all she had in the entire world.

"Oh Sarah," He said quietly, as he approached. She span round, emitting some sort of bark of relief and she launched herself into his arms and sobbed like he had never heard her sob before. And he swore that he would never hear her sob like that again.

"It's all my fault," she kept repeating into his shoulder, again and again. "Oh Harry, it's all my fault!"

"It's not your fault old girl," he said soothingly. "Why don't we go up to the ward, see how she's doing?"

Sarah shook her head against his shoulder and tightened her grip around his neck a little more.

"I argued with her Harry! Then she just sort of, clutched at her arm, and gagged and fell to the floor! I did it! I got her all riled up!" Sarah coughed out in snatches. "Please don't hate me! I couldn't bear losing you too."

"I don't hate you old girl," Harry said quietly, pulling Sarah's arms apart to look at her face. "I could never hate you! Especially for something that wasn't your fault. Your aunt loves a good argument more than even you do. And heart attacks are a ticking time bomb. Now you listen to me, Sarah-Jane Smith _It was not your fault_. Understand?"

Sarah hiccupped a little, and nodded slightly.

"Now, you hold it together old girl, ok?" Again she nodded, looking slightly calmer. So Harry took the risk in riling her up. "I've seen you do battle with all sorts of unimaginable creatures without batting an eyelid."

"But they're not family," she said in a broken voice. "Oh Harry, I won't have anyone! In the whole wide world it'll just be me. Alone."

"Now, you listen here old girl," Harry said sternly, guiding Sarah into the hospital "You will always have me. And you will always have the Brigadier, and Benton. No matter what. If one of us is alive, then you have family. You are family to us now old girl, and you are most definitely not getting rid of me any time soon!"

Sarah gave his a ghost of a watery smile and led him to were her Aunt was sleeping.

….

"Harry will be here in half an hour Aunt Lavinia," Sarah said brightly a few weeks later. Her aunt was weak, needed watching for most of the time and resented any implication that she needed any help.

"Oh?" She said acidly "And where are you two off too?"

"_I_ am going to the local planning office, there might be a story in that new factory they're building out by Ealing," Sarah said breezily, pretending not to notice that "Harry is making dinner for the three of us. Given how neither you or I can cook."

"Hmph," was Lavinia's only reply

When Harry had arrived and Sarah had gone, Lavinia indicated that Harry should take the seat next to her. He sat there, looking awkward, for a good few minutes as she scrutinised him.

"You'll look after her," she said eventually, with an air of absolute conviction. "She doesn't think she needs it, but you've been looking after both of us for a long old time now lad."

"Um, thank you? Miss Smith?" Harry said uncertainly, wondering what she was getting at.

"Now, you listen here lad," Lavinia said, as ferociously as she could (and even only operating on half her usual energy reserves, she was still pretty formidable) "I'm getting on. I reckon I've got another year, maybe two. Then I'll be joining my brother. Promise me that you'll look after Sarah?"

"You don't promise to look after Sarah," harry said with a slight affectionate smile. "Sarah agrees to let you look after her. And one day, I hope she'll agree."

"I just hope I'm still alive to see Sarah in her mother's white dress," Lavinia said pointedly. Harry spluttered and flailed a bit. "I have eyes lad. So don't you try to pull the wool over them."

…..

Harry had been acting strangely the last few days, Sarah thought. He still came over frequently, would call her if he couldn't make it, or offer to make dinner for her and Aunt Lavinia. But, he was just…off. He was distracted, like he was thinking about something else constantly, worrying over something. And sometimes, she had caught him staring at her, brow furrowed, before he'd blush a bit and glance away. She was worried about him. She had even phoned Benton, to ask if anything had happened at UNIT that would turn happy, jovial Harry into this solemn and reflective gentleman. Benton hadn't known anything.

So Sarah decided to ask him straight out. When he came over for dinner and after Lavinia had gone to bed.

"What's wrong?" She asked, handing him the usual glass of wine as she sat down on the armchair next to him on the sofa. "You've been acting odd for days. Anything I can help with?"

"Its nothing," Harry said quietly, avoiding looking at her.

"It most certainly is something," Sarah persisted "You've had me very worried! I even called Benton to ask what was wrong with you!"

That got Harry's attention. "What did he say?" He demanded anxiously.

"So it's something to do with UNIT then," Sarah concluded, frowning at him. "Harry, what's wrong!"

Harry looked torn.

"Please Harry," Sarah said quietly, knowing that he struggled turning down anything when she asked him nicely. And sure enough, Harry sighed, put his glass on the coffee table and rested his elbows on his knees.

"I've been assigned to UNIT for three years now," he said softly, eyes trained on the table. "But officially I'm contracted with the navy."

"Yes," Sarah said, confused "I know."

"But you don't know that I have been issued new orders," harry said even quieter. Sarah was sure her heart stopped beating just for a second.

"What?" She breathed in shock. "You're _leaving_?"

"It would seem so old girl," Harry sighed. Still refusing to look over to Sarah.

"But, why?"

"They need me on one of the carriers. Well, they need a doctor anyway, not specifically me."

"But you can't leave!"

"I hate having to go old girl, but I haven't got a choice in the matter," Harry sighed, picking the glass up again and knocking the wine back in one. "I can't afford civilian life."

"Harry," Sarah said, in the softest whisper. Harry finally looked over, to see her sat bolt upright, eyes wide, fear in them. "Harry, you can't leave."

Harry reached across to pull Sarah's hand into his own.

"I didn't know how to tell you," he sighed "It's why I've been acting so off the last couple of days."

"How am I going to cope without you?" Sarah said in a voice Harry was barely able to hear.

"You'll be fine old girl. You coped before me didn't you?" Harry joked, all the while wondering how he was going to cope without seeing her.

Suddenly faced with the reality of losing him, Sarah realised just how much Harry Sullivan had worked her way into her life. He had a key to her house, the spare room was unofficially 'Harry's room', they did their shopping together, he would call in the middle of the day to talk to her. He was always there, and suddenly, the prospect of even a day without Harry seemed terrifying. Harry was her rock. She felt her heart break a little. And then, another realisation made itself quite clear. After all this time. She loved him! Even with his old fashioned, private schoolboy ways.

"If I asked you to stay?" Sarah turned to Harry, looking him straight in the eyes, pleading with him. She saw his eyes widen slightly.

"If I could," he said softly, raising a hand to her cheek. "I truly, _honestly_ would."

"We could have had a quiet practice in the country," Sarah joked weakly, tears in her eyes. Her raging feminist side hated the principle of giving everything up for one man, but her emotions were fiercely arguing back that it wasn't just any man, it was _Harry._

"You'd have hated it," he joked back. "You like the city too much."

"Small village near the city then," She compromised.

"Maybe one day," Harry seemed to be questioning her. When I leave the navy, he seemed to be promising, will you agree then?

"Yes," She agreed, a sad smile on her face, "Maybe one day."


	2. Chapter 2

He had been gone ten weeks, five days and seventeen hours when Sarah pulled up in the UNIT HQ to speak to the Brigadier. He had another twenty-nine weeks, one day and seven hours until his ship would be docked in Portsmouth and he would be on leave. To say she was counting down was an understatement.

"Hello Alistair," She said warmly, shaking the older gentleman's hand. "How have you been?"

"I've been very well Miss Smith, and yourself?" He enquired with a smile, indicating for her to take the seat opposite his desk.

Hmm, how had she been? Considering how no-one knew of her somewhat odd relationship with Harry, he must be expecting a generic answer.

"Oh, you know me," Sarah said lightly with a smile "I keep soldiering on."

"Hmm," The Brigadier didn't look convinced. He confirmed her suspicions when he followed this up with "How long has Sullivan been at sea?"

"Nearly eleven weeks," Sarah looked at her hands. She felt weak for missing him so much. They had letters, but even they were few and far between. "Only another thirty or so to go hey?"

"Yes, quite," The Brigadier appeared to be scrutinising her quite thoroughly. "I must remember to put in my letter to him that you appear to have not been eating properly."

Sarah's head snapped up defiantly. "I have too been eating!" she insisted "And why would you tell Harry such a thing?"

"Before he left, he asked that myself and Benton make sure you don't feel too out of the loop," the Brigadier smirked slightly. "You're not a wife you see, so he was afraid they wouldn't tell you anything."

"They don't," Sarah said hotly, slumping back in her chair.

"No, of course not. I however, am able to hear from him on a more regular basis than family. He's missing you too, keeps asking about you whenever I speak to him."

Sarah looked up suddenly, hope in her eyes. "I just want him to come home, where I know he is safe. I'm not used to him being the one in danger. Usually it's me."

"Now you know how he feels," The Brigadier smirked.

"Alistair," Sarah asked slowly. "How does one go about leaving the armed forces?"

"Well, I don't think you have to worry about that Miss Smith, by the end of this tour, our Doctor Sullivan will be able to afford his own quiet, not quite country practice."

Sarah blushed.

"I've been saving too," she admitted with a soft smile. "I just want to hear his voice again."

"Well," The Brigadier's smirk grew a little bit more. Sarah narrowed her eyes at him suspiciously. "Do you fancy seeing a few of your old haunts while you're here? I believe Benton is in the lab talking to our new scientist. Nice chap, bit young though. Liz Shaw recommended him."

"What are you planning Alistair?" Sarah asked suspiciously. "I speak to Benton often enough."

"Yes, but I need to speak to Chesterton anyway about some analysis he's working on, Benton will be glad to see you."

And with that, he stood up, picked up his infernal cane and moved to open the door for Sarah. He raised his eyebrow at her pointedly. With a huff that let him know how she disliked being ordered around, Sarah stood up to follow.

She felt a wave of nostalgia for her time with the Doctor, for all the times she had spent, wandering these familiar corridors to the lab, for the times spent not understanding a word of what he was saying, for his opera coat being slung over the arm of a chair. For finding Harry tied up with a skipping rope in the cupboard just after the Doctor had regenerated into all hair and teeth and scarf.

She heard a bubble of voices from behind the door. The Brigadier knocked (just to be polite) and entered, holding the door for Sarah to enter.

John Benton was stood lounging against a desk, snapping to attention when he saw the Brigadier, chatting away to a handsome man Sarah didn't recognise with smart dark hair and a white lab jacket on. The stranger smiled widely at her, moving forward to shake her hand

"Hallo," he grinned in a friendly manner "You must be the infamous Miss Sarah-Jane Smith. Nice to meet you. I'm Ian Chesterton."

"Nice to meet you," Sarah said sincerely with a smile. "And what do you mean 'infamous'? Have the boys been talking about me?"

Ian laughed heartily. Sarah decided she liked him, he had a very direct and forthright personality.

"Yes, I rather suppose they have," He grinned "I hear you used to get into all sorts of scrapes, even when they left you doing the supposedly safe jobs."

"Well," Sarah pretended to huff. "I can look after myself! They didn't need to keep mollycoddling me."

"Well, forgive us for wanting to keep you fighting fit and causing quite the stir," A new voice that Sarah knew very well said, from somewhere to here right. Sarah turned around quickly, not quite believing it. He was on a ship, hundreds of miles away in the middle of the ocean. She had received a letter from him dated only a few days prior just this morning.

"Harry?" She asked in disbelief as he stood up from a chair in the corner, hands in the pockets of a white lab coat. He looked a bit sheepish.

"Hallo old girl," he said with a smile. Sarah laughed before striding forward, meeting him halfway in a hug. She didn't want to let go. She breathed in the familiar, comforting smell of Harry. "I've missed you." He whispered in her ear.

"And I've missed you," Sarah replied, giving him a tighter squeeze before letting go. She turned around to the Brigadier, with Harry keeping one arm firmly round her waist. "How did you manage this? I got a letter from him just this morning!"

"I told them I needed Harry specifically for a mission," The Brigadier smirked. "And I do need him, for a few days at least. But I could have made do with any medical professional, Harry having studied alien physiology was just a bonus. You two have three days before Harry needs to be going back to the ship."

Sarah pulled free from Harry to throw her arms around the Brigadier's neck. She planted a quick kiss of his cheek. "Thank you Alistair!" she grinned, before turning round to all the others. "That was a mean trick," She said, attempting to be stern but not quite managing It over the huge smile on her face.

"it was my idea," Harry said, attempting to save the others. He grinned. "It was either this or turn up at your house at six this morning. I didn't think you, miss I-dislike-waking-up or your aunt, would appreciate my ringing the doorbell at that time."

"I wouldn't have minded," Sarah said happily, threading her fingers through his. "Do you have to stay on site?"

"Nope," Harry grinned, "I've actually finished all the Brigadier wanted me to do. Shall we go and give your Aunt another heart attack?"

"Don't joke Harry!" Sarah swatted his arm. "She's missed you too."

"Well, she's probably missed my cooking if nothing else!" Harry joked.

"Cheeky," Sarah muttered.

A sharp cough made them remember everyone else in the room.

"Oh, sorry, were we making you feel uncomfortable," Sarah teased. Benton and Chesterton were sporting barely concealed grins while the Brigadier looked distinctly unimpressed.

"When you're next on leave Harry," Ian said, "You and Miss Smith should come over for dinner with me and my wife. We can exchange stories about the Doctor and his inability to drive his infernal ship."

"I will old chap, I get the feeling Sarah will like your wife very much," Harry grinned, shaking hands with the younger looking man. Sarah shook his hand as well, privately thinking that, so long as the woman wasn't a child obsessed housewife, yes, they probably would get on very well indeed.

"And Miss Smith," Ian turned to her "It was lovely meeting you. If you feel like you're short of company, Barbara and I would love to have you over for dinner. Get some proper food in you."

"Cheek!" Sarah grinned, giving Benton a kiss on the cheek and shaking Alistair's hand. "Well, see you in a few days."

"Bye!" The men chorused as Sarah and Harry left, hand in hand.

"So darling," Sarah said conversationally. "What exactly have you been telling poor Chesterton about me?"

**A/N I know that this is REALLY not how its done on ships – leave can be arranged, but I kinda wanted the Brig to have a hand in helping them along. I bet he's an old softie underneath all the bluster. **


End file.
